This invention relates generally to solid-state electronic watches, and more particularly to a solid-state watch movement receivable within a watch case having an end window, the movement including a module whose obverse face is viewable through the window and has mounted thereon the electro-optical stations of a time display.
The term "solid-state watch," as used herein, is limited to timepieces provided with an electro-optic time display and having no moving parts. In electronic watches which have a moving-hand read-out, the oscillations at a balance wheel or the vibrations of a tuning fork resonator are electrically sustained. These oscillations or vibrations are converted into rotary motion for driving a gear train which turns the hands of the watch; hence such electronic timepieces are not properly designated solid-state watches.
Since the works of a traditional mechanical watch or of a tuning-fork electronic watch received within a watch case are usually referred to as the "movement," this term will be retained herein for a solid-state watch, despite the absence of any moving parts, thereby distinguishing between the case and the works contained therein.
In the typical solid-state watch, such as the watches disclosed in U.S. Pat. Nos. 3,756,103 and 3,759,031, low-frequency electrical pulses derived from a high-frequency crystal-controlled time base serve to actuate a multi-digit electro-optical display formed either by light-emitting diodes (LED) or by liquid-crystal display elements (LCD), no moving parts being entailed. In such solid-state watches, the output of the quartz-crystal oscillator is fed to a frequency converter constituted by a chain of divider stages. Low-frequency timing pulses yielded by the converter are applied to a display actuator in the form of a miniature time-computer that counts the input train, encodes it in binary form and then decodes and processes the resultant data to provide appropriate activating signals for the display stations.
The power requirements for an LED time display are high, and should the display be continuous, the life of the miniature power cell installed in the watch would be brief. It is for this reason that commercially available watches having an LED display are normally quiescent, the display being turned on only when the user depresses a demand switch.
In one such LED watch, the display is programmed so that with a momentary depression of the demand switch, the minutes and hours are indicated--whereas continued depression of the switch causes the minutes and hours to fade and the seconds to appear and to count as long as the demand button is held in. In this type of arrangement, which is disclosed in U.S. Pat. Nos. 3,560,990; 3,576,099 and 3,664,118, precise computation of time is continuous and independent of whether or not it is displayed, so that the moment one touches the demand switch, timing signals are applied to the display.
Of particular interest in the context of the present invention is the U.S. Pat. No. 3,803,827 of Roberts, the disclosure of which is incorporated herein by reference. In the solid-state LED watch illustrated in this patent, the movement is formed by a one-piece frame which houses the entire wrist-watch assembly, including a pair of power cells and crystal oscillator and a trimmer capacitor. The LED display stations are mounted in a package placed on the frame and are viewable through the window on top of the watch case. Ready access may be had to the power cells and the trimmer capacitor by removal of the back of the watch case.
While the modular solid-state watch construction disclosed in U.S. Pat. No. 3,803,827 facilitates the assembly, adjustment and repair of the movement and makes it easy to replace the batteries, a large number of leads and other discrete conductors are required to make connections to terminals of the time display LED package and connections to the terminals of the integrated circuit forming the electronic timekeeping system. Thus in putting together a solid-state watch of the type disclosed in this patent, it is not simply a matter of fitting modules together within a case, for an elaborate hook-up procedure is involved which adds substantially to the cost of producing such watches.